Why is my duplicated mesh acting goofy?
I think I have figured it out. It has to do with the shape keys I was experimenting with. I had a shape key assigned to the jaw to make the mouth move. Apparently attaching the teeth to the jaw after the key was assigned is not a good practice. I believe that's what led to the teeth expanding and moving out of place. I am going to remove that shape key, create the teeth, and then redo the shape key. If that doesn't fix things, I'll be back!